Showing papers on "Bioaccumulation published in 1994"
01 Jan 1994
TL;DR: In this article, the authors describe protocols for testing freshwater organisms in the laboratory to evaluate the toxicity or bioaccumulation of contaminants associated with whole sediments, including the amphipod Hyalella azteca and midge Chironomus tentans.
Abstract: Procedures are described for testing freshwater organisms in the laboratory to evaluate the toxicity or bioaccumulation of contaminants associated with whole sediments. Sediments may be collected from the field or spiked with compounds in the laboratory. Toxicity methods are outlined for two organisms, the amphipod Hyalella azteca and the midge Chironomus tentans. The toxicity tests are conducted for 10d in 300-mL chambers containing 100 mL of sediment and 175 mL of overlying water. Overlying water is renewed daily and test organisms are fed during the toxicity tests. The endpoint in the toxicity test with H. azteca is survival and the endpoints in the toxicity test with C. tentans are survival and growth. Procedures are primarily described for testing freshwater sediments; however, estuarine sediments (up to 15% salinity) can also be tested with H. azteca. Guidance for conducting 28-d bioaccumulation tests with the oligochaete Lumbriculus variegatus is provided in this manual. Overlying water is renewed daily and test organisms are not fed during bioaccumulation tests. Methods are also described for determining bioaccumulation kinetics of different classes of compounds during 28-d exposures with L. variegatus.
819 citations
TL;DR: In this paper, it was shown that yeast cells in suspension accumulate heavy metal cations such as Cu2+, Co2+, and Cd2+ in a wide range of ambient conditions.
Abstract: Yeast cells are capable of accumulation of various heavy metals, preferentially accumulating those of potential toxicity and also those of value. They retain their ability to accumulate heavy metals under a wide range of ambient conditions. In the present study it was shown that yeast cells in suspension accumulate heavy metal cations such as Cu2+, Co2+. The level of copper accumulation was dependent on the ambient metal concentration and was markedly inhibited by extremes of ambient pH. Temperature (5–40°C) and the presence of the alkali metal sodium had much smaller effects on the level of copper accumulation. This suggests that in waste-waters of pH 5.0–9.0, yeast biomass could provide an effective bioaccumlator for removal and/or recovery of the metal. During bioaccumulation and subsequent processes it is necessary to retain the biomass. It was shown in the present study that this could be achieved by cell immobilization. Immobilization allowed for complete removal of Cu2+, Co2+, and Cd2+ from synthetic metal solutions. The immobilized material could be freed of metals by use of the chelating agent ethylenediamine tetraacetic acid (EDTA) and recycled for further bioaccumulation events with little loss of accumulation capacity.
293 citations
TL;DR: Mussels and benthic fishes were the best indicators of coastal pollution in the water column and sediments, respectively, although the above features should not be overlooked in the interpretation of biomonitoring data.
Abstract: Hydrocarbons and polychlorinated biphenyls (PCBs) were determined in tissues of marine organisms (mussels, crabs, benthic, and pelagic fishes) from six sites along the Catalan Coast (Western Mediterranean). Both aliphatic and aromatic hydrocarbons as well as seven PCB congeners (PCB-28, 52, 101, 118, 138, 153, 180) were quantified and differences in concentrations interpreted in terms of geographical distribution, trophic level, and biological cycle of the organisms. The bioaccumulation patterns of the different chemicals varied substantially. Hydrocarbons were metabolized along the food web, contrarily to PCBs, which exhibited a higher bioaccumulation in fishes. Considering 36 peaks of the GC-ECD profiles, encompassing 40 PCB congeners, from tri- to octa-chlorinated isomers, a relative enrichment was observed in the higher chlorinated ones from: mussels < mullets < tuna < crabs. The slopes of the correlation plots between the bioconcentration factor (log BCF) and the octanol-water partition coefficient (log Kow) for the different PCB congeners reflected the feeding behavior of the organisms, mussels exhibiting a preferential uptake by direct partitioning from water, and mullets and crabs with a certain uptake from sediments. Increasing metabolic degradation following a similar trend among species was also observed for aromatic hydrocarbons and PCB congeners containing meta and para vicinal H-atoms. Accordingly, mussels and benthic fishes were the best indicators of coastal pollution in the water column and sediments, respectively, although the above features should not be overlooked in the interpretation of biomonitoring data.
268 citations
TL;DR: In this paper, the authors explored the chemical and ecological factors that determine the bioaccumulation of radiocesium in fishes, and found that the fish bioaccume of 137C by fish was a negative function of both dissolved potassium and suspended sediment concentration, and a positive function of temperature.
Abstract: Although many measurements have been made on radiocesium levels in water and aquatic biota, no agreement has been reached regarding the factors affecting bioaccumulation of these radionuclides. With monitoring data from countries that operate nuclear facilities and data from the primary literature, we explored the chemical and ecological factors that determine the bioaccumulation of radiocesium. Using log–linear regression we found that the bioaccumulation of 137Cs by fish was a negative function of both dissolved potassium and suspended sediment concentration, and a positive function of temperature. Important ecological factors were the trophic level of the fish (piscivores bioaccumulate more than plank-tivores and benthivores), and the length of the food chain as reflected by the ratio of piscivore yield relative to net primary production. Fish from softwater drainages, which make up a large portion of northern Europe and Canada, are more vulnerable to radiocesium contamination than fish from hardwater ...
187 citations
TL;DR: The risk assessment for bioaccumulation presented here is more comprehensive than the EU Technical Guidance Document (TGD) for new and existing substances and takes into account the complexity of bio Accumulation processes including uptake and depuration kinetics, bioconcentration factor, metabolism, and bound residues, relating these data to critical body burden concentrations.
185 citations
TL;DR: Normalization of BAFs to the phospholipid fraction reduced species variability for the more hydrophobic congeners, supporting the hypothesismore » that these compounds have restricted membrane permeability.
Abstract: Experiments were conducted to compare the bioaccumulation of hydrophobic compounds among different phytoplankton divisions, and to evaluate the factors that affect species-specific differences. Unialgal batch cultures of Selenastrum capricornutum, Anabaena sp., and Synedra sp. were exposed to 40 PCB congeners at 11 C for 40 d. PCBs selected for this study represented all 10 homologs, different substitution patterns, and a wide range of physical-chemical properties representative of compounds known to bioaccumulate in aquatic organisms. Congener-specific partitioning into the algal phase over time was investigated. Species differences were observed in the rate and magnitude of accumulation. For all species, a rapid association of PCBs with the algal phase was followed by a slower partitioning from the media to the algae, which continued for several days. Bioaccumulation factors (BAFs) could be predicted from K[sub ow] for PCB congeners with log K[sub ow] values < 6.0, whereas no such correlation was found for the more hydrophobic congeners. Normalization of BAFs to total lipid or glycolipid content reduced some of the variability between species for the less hydrophobic congeners, but not for the more hydrophobic congeners. Normalization of BAFs to the phospholipid fraction reduced species variability for the more hydrophobic congeners, supporting the hypothesismore » that these compounds have restricted membrane permeability.« less
139 citations
TL;DR: It is suggested that the bioavailability of contaminants such as those tested cannot be accurately pre dicted in bioassays that expose organisms to aqueous representations of whole sediment.
Abstract: Bioassays have frequently been used as tools to simulate exposure of benthos to sediment-associated contaminants in hazard assessments. Due to the problems involved with estimating bioavailability in whole-sediment bioassays, aqueous frac tions such as elutriates and pore water have been substituted for whole-sediment exposures. The objective of this research was to compare and evaluate the bioavailability of representative neutral hydrophobic contaminants in whole sediments and in aque ous extracts of whole sediment (elutriate and pore water) in simultaneous bioassays, using three representative indicator spe cies, Diporeia spp., Chironomus riparius larvae, and Lumbriculus variegatus. Aqueous extracts of whole sediment did not accurately represent the exposure observed in whole sediment. Generally, the aqueous extracts underexposed organisms com pared to whole sediment, even after adjusting accumulation to the fraction of organic carbon in the test media. Accumulation comparisons among whole-sediment, elutriate, and pore-water exposures depended on sampling time. At some sampling times for some contaminants, differences in accumulation between a particular aqueous extract and whole sediment were not signifi cant; however, these similarities were not observed for all species at the particular sampling time. Bioaccumulation and con taminant clearance data suggest that a number of factors such as the indicator species, exposure media, and chemical/physical properties of individual contaminants are responsible for the accumulation differences observed among the tested media. Nor malizing bioaccumulation to the amount of organic carbon in a source compartment adjusted for bioavailability differences of only some contaminants. We suggest that the bioavailability of contaminants such as those tested cannot be accurately pre dicted in bioassays that expose organisms to aqueous representations of whole sediment.
134 citations
Book•
01 Feb 1994
TL;DR: In this article, the authors present a method for the analysis of polluted soil by measuring microorganisms' activities and the presence of organic compounds in soil organic matter, and compare the effects of different inputs of Pesticides and Fertilizers on Soil Organisms.
Abstract: Introduction: Ecotoxicology of Soil Organisms: Seeking the Way in a Pitch Dark Labyrinth (H. Eijsackers). Occurrence and Fate of Contaminants in Soil: The Pollution of Soils and Groundwater in the European Community (L.H.M. Kohsiek, D. Fraters, R. Franken, J. Latour, A.M.A. van der Linden, R. Reiling, and W.J. Willems). The Consequences of Bound Pesticide Residues in Soil (A. Calderbank). Formation and Binding of Chlorinated Anilines to Soil Organic Matter (M. Mansour, W. Volkel, I. Scheunert, and F. Andreux). Effects on Organisms: Soil Microoganisms of Global Importance to Consider Ecotoxicology in an Economical and Ecotoxicological Way (P. Doelman and J.W. Vonk). A Method for the Ecotoxicological Risk Analysis of Polluted Sediments by the Measurement of Microbial Activities (P. van Beelen and P.L.A. van Vlaardingen). Biosensors for Pollution Monitoring and Toxicity Assessment (A.L. Atkinson and D.M. Rawson). The Effects of Heavy Metal Contaminated Sewage Sludges on the Rhizobial Soil Population of an Agricultural Field Trial (J.P. Obbard and K.C. Jones). Effects of Heavy Metals, Organic Substances and Pesticides on Plants (J.A.C. Verkleij). Phytotoxic Organic Compounds in Spruce Forest Soil: Chemical Analyses Combined with Seedling Bioassays (A.B. Steen, H. Boren, and A. Grimvall). The Yorkshire Water Standard Plant Growth Trial for Toxicity Testing of Soils, Sludge and Sediments (P.D. Hiley and B. Metcalfe). The Use of Barley Root Elongation in the Toxicity Testing of Sediments Sludges and Sewages (P.D. Hiley). Accumulation of Putrescine in Chromium Exposed Barley and Rape: A Potential Biomarker in Higher Plants (M.Z. Hauschild). Ecotoxicological Test Systems for Terrestrial Invertebrates (C.A.M. van Gestel and N.M. van Straalen). Comparison of Effects of Two Pesticides on Soil Organisms in Laboratory Tests, Microcosms and in the Field (J. Rombke, Th. Knacker, B. Forster, and A. Marcinkowski). Species-Specific Sensitivity Differences of Earthworms to Pesticides in Laboratory Tests (H. Kula). Usefulness of Testing with Eisenia foetida for the Evaluation of Agrochemicals in Soils (G. Diaz Lopez and R. Mancha). A Prolonged Laboratory Test on Sublethal Effects of Pesticides on Eisenia fetida (C. Kokta). The Development of Soil Toxicity Test Systems with Lumbricids to Assess Sublethal and Lethal Effects (W. Kratz and R. Pohhacker). Assessment of Pesticide Safety to the Carabid Beetle, Poecilus cupricus, Using Two Different Semi-Field Enclosures (U. Heimbach, P. Leonard, R. Miyakawa, and C. Abel). An Index of the Intrinsic Susceptibility of Non-Target Invertebrates to Residual Deposits of Pesticides (J.A. Wiles and P.C. Jepson). Effects of Different Input of Pesticides and Fertilizers on the Abundance of Arthropods in a Sugar Beet Crop: An Example for a Long Term Risk Assessment in the Field (W. Buchs). Effects of Walking Activity and Physical Factors on the Short Term Toxicity of Deltamethrin Spraying in Adult Epigeal Money Spiders (Linyphiidae) (G. Jagers op Akkerhuis). Bait-lamina as a Tool for Testing Feeding Activity of Animals in Contaminated Soils (O. Larink). Uptake, Assimilation and Ligand Binding of Cadmium and Zinc in Helix pomatia After Combined Exposure to Both Metals (B. Berger, R. Dallinger, A. Gruber, and J. Moser). Bioaccumulation and Food Chain Transfer: Methodological Principles of Using Small Mammals for Ecological Hazard Assessment of Chemical Soil Pollution, With Examples on Cadmium and Lead (W. Ma). Heavy Metal Tissue Levels, Impact on Breeding and Nestling Development in Natural Populations of Pied Flycatcher (Aves) in the Pollution Gradient From a Smelter (N.E.I. Nyholm). A Method to Assess Biorisks in Terrestrial Ecosystems (A.M. Abdul Rida and M.B. Bouche). Ecotoxicological Assessment Procedures: Progressing Limits for Soil Ecotoxicological Risk Assessment (N.M. van Straalen, P. Leeuwangh, and P.B.M. Stortelder). Ecotoxicological Extrapolation: Tool or Toy? (H. Lokke). A Case Study on Bioindication and Its Use for the Assessment of Ecological Impact (H.H. Koehler). On the Effects of Pesticides at the Ecosystem Level (K. Mathes).
134 citations
TL;DR: In this paper, samples of sediment and eel taken from six sites in Amsterdam with different levels of water pollution were analyzed for 16 parental PAHs and biliary PAH metabolites and hepatic PAH-DNA adducts were determined in the eel to evaluate biomomtoring techniques for PAH exposure.
Abstract: Samples of sediment and eel taken from six sites in Amsterdam with different levels of water pollution were analyzed for 16 parental PAHs In addition, biliary PAH metabolites and hepatic PAH-DNA adducts were determined in the eel to evaluate biomomtoring techniques for PAH exposure There was a clear difference between PAH profiles in sediments and eel Mainly two- and three-ring PAHs were detected in eel, whereas four-ring PAHs predominated in the sediments Because PAH bioaccumulation was highest in eel from the reference sites, tissue levels of the parental PAH are probably not the most accurate monitor of PAH exposure in fish An elevated excretion of 1 OH pyrene (determined by synchronous scan fluores cence) was observed in the bile of fish from three of the four polluted sites, indicating that this parameter may be used as a biomarker for PAH exposure A significant increase in PAH-DNA adduct levels (determined by 32P postlabeling) was observed in the liver of eel from all polluted sites Therefore, this parameter seems to be a sensitive biomarker for exposure to mutagenic and carcinogenic PAHs
102 citations
TL;DR: Reductions in the feeding rate of Gammarus pulex proved to be a sensitive indicator of the impact of metalliferous effluents on receiving water quality and iron was a major toxicant.
77 citations
TL;DR: The bioaccumulation and elimination of organotin compounds in Pagrus major during dietary uptake and/or direct uptake from water were studied in this article, where the assimilation efficiency of ingested TBT and TPT was 9.5 to 12.7 and 19.6 to 24.6%, respectively.
Abstract: The bioaccumulation and elimination of organotin compounds in Pagrus major during dietary uptake and/or direct uptake from water were studied. When tributyltin (TBT) and triphenyltin (TPT) compounds were accumulated in fish from seawater and from feed simultaneously, about one-quarter of the bioaccumulation was due to the dietary uptake. The biomagnification factors (BMFs) were 0.26 to 0.38 for TBT and 0.57 for TPT. BMF was not significantly altered by the concentration nor the species of chemicals in the feed. The assimilation efficiency of ingested TBT and TPT was 9.5 to 12.7 and 19.6%, respectively, and percentage retention was 24.2% for TBT and 60.1% for TPT. The BMF, percentage retention, and assimilation efficiency of TBT were all lower than those of TPT, suggesting that TPT compounds are more easily accumulated by dietary uptake than TBT compounds. Compared to PCBs and methylmercury chloride, the assimilation efficiency and the percentage retention of organotin compounds were low. These lower values imply that the risk of bioaccumulating the ingested organotin compounds might be smaller than for PCBs and methylmercury chloride.
TL;DR: It is indicated that sediment is a significant source of metals to invertebrates in the Clark Fork River and long-term monitoring of the river should include sampling benthic invertebrate for metal accumulation.
Abstract: Macroinvertebrate contaminated with metals in the Clark Fork River of Montana have been demonstrated to be a potentially toxic component in the diet of trout. Because sediment was the suspected source of metals to these invertebrates, bioaccumulation of As, Cd, Cu, Pb, and Zn from sediment was evaluated by exposing the amphipod Hyalella azteca for 28 d in the laboratory to samples of sediment collected from depositional areas of the Clark Fork River. Benthic invertebrates collected from riffles adjacent to the depositional areas were also analyzed for metals. The pattern of metal accumulation between laboratory-exposed and field-collected animals was similar; however, the concentrations of metals in laboratory-exposed amphipods were often 50 to 75% less than were the concentrations of metals in the field-collected invertebrates. These findings indicate that sediment is a significant source of metals to invertebrates in the Clark Fork River. Additional studies should be conducted to determine threshold concentrations for effects of dietary metals on fish. Long-term monitoring of the river should include sampling benthic invertebrates for metal accumulation.
TL;DR: In this paper, a 30-day exposure to the test sediments, Lumbriculus variegatus contained concentrations of metals not significantly greater than those in control oligochaetes exposed only to Lake Superior water.
TL;DR: Results of laboratory, mesocosm, and field studies on the toxicity of sewage sludge to marine organisms are summarised and acute toxicity is unlikely to occur at ecologically significant or detectable levels at dump sites, however, at some dump sites chronic effects due to organic enrichment are evident as changes in the species richness, relative abundance, and biomass of macroinvertebrate species.
TL;DR: Cross-flow microfiltration was shown to retain Saccharomyces cerevisiae biomass utilized for heavy metal bioaccumulation through a series of sequential bio Accumulation systems, allowing for further reductions in the levels of copper, cadmium, and cobalt in the final effluent than that afforded by a single bioaccUMulation process.
Abstract: Cross-flow microfiltration was shown to retain Saccharomyces cerevisiae biomass utilized for heavy metal bioaccumulation. The passage of metal-laden influent through a series of sequential bioaccumulation systems allowed for further reductions in the levels of copper, cadmium, and cobalt in the final effluent than that afforded by a single bioaccumulation process. Serial bioaccumulation systems also allowed for partial separation of metals from dual metal influents. More than one elemental metal cation could be accumulated simultaneously and in greater quantities than when a single metal was present in the effluent (Cu2+ 0.43 mmol, Cu2+ + Cd2+ 0.67 mmol, and Cu2+ + Co2+ 0.83 mmol/g yeast dry mass when the initial concentration of each of the metal species was 0.2 mmol·L−1). Co-accumulation of two different metal cations allowed higher total levels of bioaccumulation than found with a single metal. The flux rate was 2.9 × 102 L·h−2μm−2 using a polypropylene microfiltration membrane (0.1 μm pore size) at 25°C. © 1994 John Wiley & Sons, Inc.
TL;DR: Levels of zinc, iron, copper, chromium, cobalt, cadmium and lead were determined in some organs and body muscles of Illisha africana fish, water and sediments from three neighbouring man-made freshwater ponds using an atomic absorption spectrophotometer.
Abstract: Levels of zinc, iron, copper, chromium, cobalt, cadmium and lead were determined in some organs and body muscles of Illisha africana fish, water and sediments from three neighbouring man‐made freshwater ponds using an atomic absorption spectrophotometer. The ponds were located at the Research Farm of the Ondo State College of Education, Ikere‐Ekiti, Ondo State, Nigeria. The water levels of these metals were found to be much lower than their corresponding concentrations in the sediments, but the levels in the sediments were less than those in the fish. Lead, iron and copper were found to be highly concentrated in the fish organs showing some likely evidence of bioaccumulation, while chromium was not detected in any of the samples whereas cobalt was not bioaccumulated in the fish organs. However, the metals concentration in the fish body muscle was low. A chemical analysis of fish, water and the sediment has to be carried out to monitor the correlation of the trace heavy metal pollutants resulting from the ...
TL;DR: It appears that contaminant bioavailability can be altered by the addition of uncontaminated food, however, this phenomenon appears to be compound-specific and not broadly predictable.
TL;DR: The development of dose-response relationships for polycyclic aromatic hydrocarbons (PAH) present in sediment, in relation to bioaccumulation in flatfish, is of major interest for evaluating the environmental effects of oil contamination.
Abstract: Pseudopleuronectes americanus were chronically exposed to Hibernia crude oil in sediments, for 4 months. Oil was added to sediments at five concentrations between 0.09 and 4.5 mg/g (dry weight) and was 0.10-0.90 mg/g, at the termination of the exposure. Bioaccumulation measured in terms of fluorescence or in terms of the concentration of specific aromatic targets, increased with dosage. Accumulation of hydrocarbons was observed in muscle tissue (0.22 microgram/g, dry weight), when concentration of the sum of 27 polycyclic aromatic compounds (PAC) in sediments was of 0.65 microgram/g (E-50), at the end of the 4-month period. Of the 27 parental and alkylated polycyclic aromatic compounds analyzed, alkylated naphthalenes predominated in muscle (90-100%) and in sediments (30-60%). Bioaccumulation factors were derived for 13 compounds detected in muscle, at the three higher exposures. Liver concentrations (fluorescence) were higher than in muscle, but did not display a noticeable dose-response. Several alkylbenzenes, a C-2 biphenyl and C-4 acenaphthene were also detected in muscle extracts. The development of dose-response relationships for polycyclic aromatic hydrocarbons (PAH) present in sediment, in relation to bioaccumulation in flatfish, is of major interest for evaluating the environmental effects of oil contamination.
TL;DR: In this paper, a northern Canadian river system has been analyzed for poly-chlorinated dibenzo-p-dioxins (PCDDs), polychlorinated Dibenzofurans (PCDFs), and extractable organochlorines (EOCl) downstream of a bleached-kraft mill.
Abstract: Abiotic and biotic environmental compartments in a northern Canadian river system have been analyzed for poly-chlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and extractable organochlorines (EOCl) down-stream of a bleached-kraft mill. The water column, deposited and suspended sediments, invertebrates, and tissues from several fish species were analyzed. The data indicate that (a) conversion of the mill bleaching process to 100% chlorine dioxide virtually eliminated the discharge of PCDDs and PCDFs; (b) PCDD, PCDF, and EOCl transport occurred primarily in suspended sediments; and (c) the food choice of filter-feeding insects by specific fish species such as the mountain whitefish (Prosopium williamsoni) was an important determinant in the food-chain transfer of the principal compounds, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and 2,3,7,8-tetrachlorodibenzofuran (TCDF). Relative to mountain whitefish, TCDD and TCDF levels in another bottom feeding species, longnose sucker (Catostomus catostomus), were at least an order of magnitude lower. Food-chain biomagnification of TCDD and TCDF was not observed in omnivorous and predatory species, burbot (Lota lota) and walleye (Stizostedium vitreum), for which lipid-adjusted levels were similar to those in the longnose sucker. These data indicate that organism lipid levels alone are not sufficient to predict species-specific bioaccumulation of these hydrophobic compounds, and that site-specific transport and species foodmore » choice parameters should be included in bioaccumulation models for hydrophobic compounds such as PCDDs and PCDFs.« less
TL;DR: The similarity between structure-activity relationships considering bioaccumulation in fishes and the Ah-affinity in mammals was discussed and several phenomena were discussed with respect to the observed bioconcentration behaviour, such as limited bioavailability, reduced lipid solubility, reduced membrane permeability and biotransformation.
TL;DR: An experimental study based on four species of rooted macrophytes was carried out to quantify and compare their mercury bioaccumulation capacity from the water column and the sediment compartments as initial sources of contamination, showing very great accumulation differences.
TL;DR: Guppies were exposed to a complex mixture of polychlorinated dibenzo-p -dioxins (PCDDs) and polychlorined dibenzofurans (PCDFs) in the presence and absence of sediment for 21 days as mentioned in this paper.
TL;DR: It is suggested that the levels of chromium in the estuary are not overtly toxic to mullet and, although short-term accumulation occurs, long-term exposure appears to lead to a stabilization in liver chromium levels.
TL;DR: In this article, an experimental study was conducted to quantify the actions and interactions of three abiotic factors (temperature: 10, 18, and 26°C; photoperiod: 6, 12, and 18 h per day; pH: 5.0 and 7.5) on inorganic mercury and methylmercury bioaccumulation by Hexagema rigida (whole organism and gills).
Abstract: Based on a three-compartment system — water, natural sediment, Hexagenia rigida nymphs — an experimental study was set up, using a complete factorial design, to quantify the actions and interactions of three abiotic factors (temperature: 10, 18, and 26°C; photoperiod: 6, 12, and 18 h per day; pH: 5.0 and 7.5) on inorganic mercury (HgCl2) and methylmercury (CH3HgCl) bioaccumulation by Hexagema rigida (whole organism and gills). The two chemical forms of the metal were initially introduced into the sediment; the exposure duration was 15 d. Total Hg burdens measured at the whole-organism level revealed a very high bioaccumulation capacity of this burrowing mayfly species and important differences between the two contamination conditions of the sediment source, a factor close to 20 observed in favor of methylmercury, for similar exposure conditions. Among the three abiotic factors taken into account, temperature and water-column pH played an important role on Hg bioaccumulated by the nymphs, when considered in isolation and in interaction. An increase in temperature from 10 to 26°C gave rise to an increase in Hg bioaccumulation, with the higher differences close to a factor of 1.7. On the other hand, acidification of the water column from 7.5 to 5.0 led to a decrease in the amounts of the metal accumulated by Hexagenia rigida. These effects were similar for the two Hg compounds, but they were more pronounced when the experimental units were contaminated by methylmercury. This comparative analysis of the amounts of metal bioaccumulated by whole organism and by the gills, estimates of nymph activity within the sediment, and results from earlier lab studies have generated several hypotheses on the involved mechanisms. We propose that ingested sediment is the predominant route of exposure and that the gut acts as a selective barrier that favors organic Hg absorption.
TL;DR: In this paper, the authors investigated the bioaccumulation rate of cadmium and lead in the mussel foot and gills and the possibility to use these organs as quantitative bioindicators of the pollution of near-shore marine environments.
TL;DR: This evaluation demonstrates that deviation from conventional assumptions used in risk assessment (e.g., negligible biotransformation and degradation; steady-state equilibrium) can significantly affect cancer risk estimates.
Abstract: We evaluated the potential cancer risk to adults from ingesting polychlorinated biphenyls (PCBs) in fish and shellfish using an equilibrium partitioning model of PCB bioaccumulation in the aquatic ...
TL;DR: As with many other animals, G. pulex was able to regulate its total body zinc level, and to accumulate most of the metal from water rather than from its food.
Abstract: The bioaccumulation of zinc by the freshwater shrimp Gammarus pulex (L.) and adsorption by its food, conditioned horsechestnut leaves (Aesculus hippocastanum L.), in two zinc exposure concentrations were studied in the laboratory. The bioconcentration factors (BCF), uptake and elimination rate constants, and assimilation rate from food were calculated for one exposure concentration using a two-trophic-level model of a food chain. The BCF of the conditioned horse chestnut leaves was more than five times higher than that of G. pulex, and the assimilation rate of zinc from food by Gammarus was only 1.4%. As with many other animals, G. pulex was able to regulate its total body zinc level, and to accumulate most of the metal from water rather than from its food.
TL;DR: In this article, the authors used lake trout and sediment data to define the biota-to-sediment ratio (BSR) for hydrophobic organic chemicals (HOCs) in Lake Ontario, including 2,3,7,8substituted polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs).
TL;DR: In this article, communities of freshwater benthic algae were exposed to water acidified daily to pH 4.8 alone and in mixtures with 50, 100, or 500 μg L−1 Al.
Abstract: Communities of freshwater benthic algae were exposed to water acidified daily to pH 4.8 alone and in mixtures with 50, 100, or 500 μg L−1 Al. Daily acidification to nominal pH 4.8 in acidified treatments exposed algae to a range of pHs that led to a variety of Al species of different toxicity. Calcium concentrations in stream water were higher in acidified and Al treatments on day 1, and dissolved Al in stream water was higher in the highest Al treatment on days 1, 7, and 28; otherwise acid and Al treatments did not significantly alter Al and Ca in the exposure water. Calcium bioaccumulation by periphyton was lower in acidified and Al treatments on all sampling days. Concentrations of Mg in water and periphyton did not differ between treatments. The artificial stream system generated alkalinity to buffer acidified water; the amount of generated alkalinity returned to approximately the same levels for the first week, but the amount of alkalinity generated during the second week appeared to decline, and acid-only and acid-Al mixtures diverged in their ability to generate alkalinity during the third and fourth weeks. Aluminum in acidified water inhibited abundance of diatoms and green and blue-green algae more than the effects of acid stress alone. The green filamentous alga Mougeotia showed a slight (but not statistically significant) increase in abundance in the acid-only treatment. The middle-Al treatment (nominally 100 μg L−1 Al and acid) generated more alkalinity and had higher abundance of some algal taxa on days 14 and 28, even though measured Al concentrations in water and periphyton fell between low- and high-Al-treatment levels. Community-level tests, combining a taxonomic analysis of algal population abundance with chemical analysis of water and bioaccumulation, provide valuable insight to assess anthropogenic stress.